Parametric EQ filters for A-weighting

[BeerBear]

I'm looking to apply the A-weighting curve with a parametric EQ, using the standard filters and frequency, gain, Q/BW values. Minimum phase preferred, but linear is fine too.

Does anyone know the correct values? (@jaakkopasanen ?)
It doesn't have to be extremely precise, but let's say good enough to get volume levels to 0.1dB precision. It can be done with fewer than 10 filters, right?

And while we're at it, also for other weightings (especially K and C).

 

[pos]

Here is the set of filters I have made for one of my plugins:
gain +2dB high pass 18Hz Q=0.4 high pass 270Hz Q=0.32 low pass 12kHz Q=0.5

The resulting curve (in red, over) is ±0.3dB compared to the 1/3 octave reference table (in blue, under).

This should be enough to get SPL readings to your intended precision.
Note: these are ideal filters, the 12kHz low pass in particular might turn out differently depending on the implementation of your filters (cramping).

 

[BeerBear]

Thanks. You're right, some EQs don't respond as intended, but it does seem to work fine in FabFilter Pro-Q3 (after multiplying the Qs by 1.41, because that's how it works).

 

[pos]

Yes, Pro Q3 does a very good job at decramping, but uses the strange convention of Q=1 instead of 0.707 for Butterworth filters.